Spark plug



Patented July 29, 1924.

PATENT OFFICE.

ROLAND T. WRIGHT, OF ST. LOUIS, MISSOURI, ASSIGNOR 'I'O WRIGHT-BUNCHER MFG; 00., OF ST. LOUIS, MISSOURI, A COMMON-LAW TRUST.

SPARK PLUG.

Application filed August 30, 1923.

To all whom it may concern:

Be it known that I, ROLAND T. WRIGHT,

a citizen of the United States, residing in the city of St. Louis and State of Missouri, have invented certain new and useful Improvements in Spark Plugs, of which the following is a specification.

My invention relates to spark plugs, and, more particularly to that of the removable core type as set out in my co-pending application, Serial Number 578,856 and has for its objects to provide a plug which has distinct and praoticalimprovements to overcome certain practical objections to, and defects in, first, the joint connection between the inner metallic core shell and the'outer main shell of the spark plug, and, second to permit the core shell to be rotated after being positioned within the outer shell but before the locking member has been applied. With the above and. other objects in view, the inventionconsists in the novel features of construction, arrangement and combination of parts hereinafter more fully described and finally pointed out in the claims hereto appended.

Referring to the accompanying drawings forming a part of this specification, wherein like characters of reference denote similar parts throughout the several views Fig.;1, isa view partly in sectional ele vation and partly in side elevation embodying the features of my invention.

Fig. 2, is a detail, partly in sectional eleva'tion and partly in side elevation clearly illustrating the non-gasket joint between the outer shell and the core holding shell.

Fig. 3, is a detail of the upper end of the outer shell in sectional elevation clearly showing the annular groove and the inclined lock grooves.

In carrying out the aim of my present invention, I employ an outer metallic shell 1 having the usual screw threaded nipple 2 at its lower end and the wrench engaging portion at its upper end. The shell 1 is provided with bores of two different diam- -eters, designated 3 and 4. These bores have straight parallel inner walls connected or united by means of along tapered shoulder 5 having the ground surface seat 6.

The inner face of the upper bore 3 is provided a suitable distance below the upper edge of the shell 1 with an internal annular groove 7 which communicates with the lower Serial No. 660,086.

ends of a pair of opposed vertically disposed grooves 8, the upper ends of which communicate with the upper face of the shell 1.

The inner face of the upper bore 3 is also provided with a pair of opposed internal inclined lock grooves 9 which are positioned I intermediate the upper edge of the shell 1 and the internal groove '7 thereof. The grooves 7 also communicate with the opposed vertical grooves 8.

10 represents an open ended core holding shell having bores of two diameters 11 and 12 and provided with the internal shoulder 13. The upper bore designated 11 is provided with internal screw threads 14.

15 indicates the porcelain or insulator core screw threads 14 of the core shell 10 for locking the insulator in removable fixed relation with the core shell. The core shell is provided with a pair of opposed radially directed ears or lugs 25 which are initially receivable in the vertical grooves 8 of the outer shell when positioning the core shell within upper bore 3 of the outer shell 1 and which are receivable in the internal groove 7 when given a slight turn after being lowered into the shell 1. This permits the core shell and insulator to be turned within the shell 1 before being locked therein and alsoprevents the core shell from falling out of the outer shell if turned upside down before being locked therein.

The lower end of the core shell 10 is slightly tapered with a concaved side sur face 26 and at the juncture of the upper end of this surface with the outer upper surface of the shell 10 there is formed a rounded or curved ground circumferential edge 26' which finds a perfect sealed seat with the surface 6 of the tapered internal ground shoulder 5 thereby preventing compressed gas leakage between the inner and outer shells and obviating the necessity of a copper gasket at this point, as will be clearly understood from Fig. 2 of the drawings.

The leak proof connection or joint just referred to is made possible through the medium of the locking collar member 27 which is provided with the opposed radially directed lugs 28 frictionally receivable in the inclined lock grooves 9 of the shell 1, which causes the lower face of the locking collar 27 to tightly engage the upper face of the core shell and force the rounded or curved ground edge of the core shell to perfectly seat itself upon the ground surface 6 of the shoulder 5 of the outer shell 1.

The locking collar or sleeve member 2? is provided wi h a pair of opposed radially directed handles 29 for manually manipulating the locking collar 27.

The upper face of the locking collar 27 is provided with a pair of upwardly directed lugs 30 which are receivable in a pair of openings or sockets 31 in the upper face of the core shell when it is desired to tighten or loosen the lock nut 24 with relation to the core shell 10.

32 represents the central electrode which passes through the insulator ore or porcelain member 15 and which is provided with the lock nut 33 and the thumb nut Set. 35 represents the ground electrode which is fixed to the lower end of the metallic core holding shell 10, so that when ever the core is removed from the outer shell, both electrodes will be removed with the core shell, hence obviating the necessity of removing the outer shell from the engine head to examine or clean the electrodes.

From the foregoing description, it is evident that I provide a spark plu is strong and durable, easy to manufacture and one which can be quickly assembled or disassembled and the provision of an air .tight joint or seatwhich is held rigid by tightening up the armed locking sleeve which seals the porcelain holding shell to the outer shell and makes the plug positively leak pro-of while eliminating a copper gasket due to my improved joint construe tion.

By providing the curved shoulder edge 26 on the core shell, it is evident that the tapered face 6 of the shoulder 5 need not be so perfectly ground as were the shoulder edge 26' also tapered. o By having the edge 26 curved, it will permit the shell to rock and find its perfect seat with the surface '6 of shoulder 5 when pressure is applied to the locking sleeve, as is'manifestn The internal: annular groove 7 isrwider than the lugs 2570f the core shell 10, as shown in I Fig. l, to permit rocking movement of the core holding shell in positioning same withinthe outer shell and also'to accommodate for possible wear on the engaging faces of the joint between the curved edge 26 of the core holding shell 10 andthe face 6 of the shoulder 50f the outer shell 1.

The many advantages of the herein de- 0 which scribed invention will readily suggestthenr selves to those skilled in the art to which it appertains.

I do not wish to be understood as having limited myself to the details of construction hown and described, but desire to have it understood that the invention 1 have 7 shown in the drawings is merely illustrative,

as it is manifest that various minor changes may be made in the exact construction and particular arrangement of parts without dea parting from the spirit of my invention, hence I reserve the right to make any such changes, or modifications as may fairly fall inclined lock grooves, an inner shell having a ground curved circumferential shoul der for contact with the ground surface of the internal shoulder of the outer shell, an insulator carried by the innershell, an electrode carried'by the insulator, an electrode carried by the inner shell and means for locking the inner shell within the outer shell for forming a tight joint between the inner shell and the outer shell. 7

2. In a spark plug construction, an outer shell provided with an internal tapered shoulder having a ground surface, a'core holding shell having a tapered lower end normally out of contact'with the tapered shoulder of the outer shell, a curved circumferential ground shoul de'r'intermediate the upper and lower edges of the core holding shell for engagement with the ground surface of the internal tapered shoulder of the outer shell, alocking sleeve carried by the outer shell having its lower face in contact with the upper face of the core holding shell, opposed radially directedhandles for the locking sleeve and a lug and groove connection between the outer shell and core holding shell to permit screw pressure being applied to the nongasket joint between the internal shoulder of the outer shell and the curved circumferential edge of the core holding shell. 7 V 3. An outer shell for spark plugs'havin a screw threaded'nipple, an internal tapere tical grooves and said shell having a pair of inclined internal lock grooves communieating at opposite ends with said vert cal grooves. r i

In testimony whereof,-l haive hereunto signed myname to the specification.

7 ROLAND T. WRIGHT. 

